Voltage pulse generator for electric fences



July 10, 1951 J. T. WESTIN 2,560,056

VOLTAGE PULSE GENERATOR FOR ELECTRIC FENCES Filed Feb. 26, 1947 FIE-/ Patented July 10, 1951 VOLTAGE PULSE GENERATOR FOR ELECTRIC FENCES Johan Torsten Westin, Stockholm, Sweden, as-

signor to Aktiebolaget Hakanssons Industrier, Amal, Sweden, a. corporation of Sweden Application February 26, 1947, Serial No. 731,098 In Sweden March 2, 1946 6 Claims. (Cl. 175373) This invention relates to a voltage pulse generator for electric fences and the like of that type which applies a constant voltage or pulse voltage to the fence and which comprises a transformer the circuits of which are designed in such a way in view of the ratio of the transformer that the maximum current which can be delivered from the voltage pulse generator is limited to a harmless value. The object of the invention is to provide a simple and reliable voltage pulse generator for this purpose having a low current consumption.

The invention is substantially characterized by the fact that in the secondary circuit of the transformer there is connected a mechanical contact device known per se which is driven electromagnetically in synchronism with the applied alternating voltage and at a suitable phase angle and which is adapted to pass current pulses of a suitable duration and voltage in one direction only (direct current). According to a preferred form of the invention the contact device comprises a pendulum consisting of a magnetized spring tuned for the same number of oscillations as the number of cycles of that current which is applied to the transformer. This pendulum may preferably be driven by means of the magnetizing flux or the leakage field of the transformer. By way of various well-known means synchronism may be obtained between the oscillations of the pendulum and the number of cycles of the secondary circuit. A direct current flow is fed to the electric fence by the contact device via its contacts. Owing to the high voltage and low current which occur in the case of electric fences, all troubles as to the construction of the contacts of the contact device are dispensed with. It is not even necessary to provide any special contact material thereon. By mean of the pendulum contact engagements of short duration are obtained which is advantageous as the time intervals between the contact engagements act as a resistance without losses, whereby the necessary resistance for obtaining a suitable time constant for the charging of the condenser generally included in the circuit of an electric fence may be reduced and possibly completely dispensed with. By permitting the short contact engagements to take place just when the voltage in the secondard winding is at its maximum, the advantage is furthermore attained that it is possible to use a transformer having a relatively low ratio of transformation.

In order to insure the contact engagements taking place just when the voltage in the secondary winding is at its maximum the pendulum can consist in a spring contact arm having a rest position and having a free amplitude of vibration extendin under normal operating con- \ditlons to an extreme position on either side of this rest position. This spring contact arm is adapted to oscillate due to the magnetic flux leakage of the transformer and to coact with a contact also connected to the secondary winding of the transformer and located in the path of the spring contact arm at a point closer to the extreme vibrating position than to the rest position so that contact will be effected only at the very moment when the vibrating arm has its maximum amplitude.

In order that the invention may be more fully understood reference is made to the accompanying drawing wherein Fig. 1 illustrates a voltage pulse generator according to the invention and Fig. 2 a modification of the invention, provided with a voltage duplicating circuit.

The transformer shown in the drawing is intended to be connected with its primary winding l to an electric network carrying an alternating current of 50 cycles. The'iron core 2 of the transformer is provided with an air gap 3 in front of which a preferably permanently magnetized leaf spring 4 acting as a pendulum and tuned to 50 oscillations per second is arranged. The free end of the spring cooperates with a contact 5 connected to one end of the secondary windin 6 of the transformer. The fixed end of the pendulum is via a lead 1 connected to earth. The secondary windin 6 is via a lead 8, through a resistor 9 and a, spark gap 10 connected to the electric fence H. At l2, l3 are shown an adjustable resistor and a condenser, respectively.

According to the embodiment disclosed in the drawing, on one limb ll of the transformer core 2 there i arranged a short-circuited winding l5 having preferably a resistance such that the phase displacement of the magnetic flux obtained thereby has the result that the pendulum makes its engagements when the voltage of the secondary winding reaches its maximum.

The operation of the device will be evident from that described above with reference to the drawing. By the engagements of the pendulum 4 with the contact 5 a pulsating direct current is obtained which charges the condenser IS. The condenser having been charged to the desired value, the voltage passes across the spark 3 gap ll, the fence wire ll being put under voltage. By the short contact engagements a sufficient time constant, 1. e. a sufllciently long time between the voltage pulses to the fence. will be obtained without using the resistor s which consequently might be dispensed with like the resistor II.

It is desirable, however, that the recharge resistor includedin the circuit be sufliciently large so that the curfent cannot arise to such a value that the contacts are damaged even upon a short-circuiting of the condenser and the maximum current which can be delivered from the voltage pulse generator due to the resistance incorporated in the circuits i limited to a harmless value.

According to the form shown in Fig. 2, the voltage pulse generator is provided with a voltage duplicating circuit, and the pendulum 4 cooperates with two contacts 5a and 5b. The circuit also comprises two condensers i6 and I1 connected in series, the condenser l6 bein connected via a lead It! to the contact 5b and through a lead l9, if desired via a spark gap III, to the fence wire ll, while condenser l1 via a lead III is connected to the contact 5a and connected to earth. With one end the secondary winding 8 is via an adjustable resistor 9a connected to the junction point between the two condensers 16, I1, and with the other end it is via another adjustable resistor Ila connected to the pendulum 4.

The operation of this device is the following: In one half cycle of the deflection of the pendulum the condenser I6 is charged and in the other half cycle the condenser ll. By coupling the two condensers I6 and H in series in such a way that one half cycle of the alternating current may charge one condenser and the other half cycle of the current the other condenser, a voltage may be derived from the outer terminals of the condenser battery, which is about two times as great as the applied voltage. The time constant of the voltage increase as well as its value is naturally dependent on the capacity, leakage current and the applied voltage of the condensers. The condensers must naturally be designed in such a way that the storage power does not exceed a certain suitable value.

As will be evident from that said above, the

voltage pulse generator may be modified in constructional respect in many ways within the scope of the invention. The voltage pulse generator may naturally be constructed for any other desired current than an alternatin current of 50 cycles.

What I claim and desire to secure by Letters Patent is:

A voltage pulse generator for supplying voltage pulses, comprising a step-up transformer having a primary winding and a secondary winding, a permanently magnetized spring comprising a pendulum contact arm connected in the circuit of said secondary winding, said spring b ng mounted adjacent the transformer to be cectromagnetically operated by means of the magnetic leakage flux of the transformer, said spring contact arm having a rest position and having a free amplitude of vibration extending under normal operating condition to an extreme position on either side of the rest position, and a contact also connected to the secondary winding and located in the path of said spring contact arm at a point closer to the said extreme position than to the said rest osition.

4 and a condenser having its terminals connec across said secondary winding and said pendulum contact arm in series, the dimensions of said condenser requiring several impulses for charging it to full voltage.

2. A voltage pulse generator for supplying voltage pulses, comprising a step-up transformer having a primary winding and a secondary winding, an alternating current source of a predetermined irequency connected to the primary winding, a permanently magnetized spring comprising a pendulum contact arm tuned to said predetermined frequency of the alternatin current source connected in the circuit of said secondary winding. said spring being mounted adjacent the transformer to be electromagnetically operated by means of the magnetic leakage flux of the transformer and in synchronism with the alternating current voltage applied from said source, said spring contact arm having a rest position and having a free amplitude of vibration extending under normal operating conditions to an extreme position on either side'of the rest position, and a contact also connected to the secondary winding and located in the path of said spring contact arm at a point closer to the said extreme position than to the said rest position, and a, condenser having its terminals connected across said secondary winding and said pendulum contact arm in series. the dimensions of said condenser requiring several impulses for charging it to full voltage.

3. A voltage pulse generator for supplying voltage pulses, comprising a step-up transformer having a primary winding and a secondary winding, substantial resistance in the transformer circuits limiting the maximal amount of current to be delivered to a harmless value, a permanently magnetized spring comprising a pendulum contact arm connected in the circuit of said secondary winding, said spring being mounted adjacent the transformer to be electromagnetically operated by means of the magnetic leakage flux of the transformer, said-spring contact arm having a rest position and having a free amplitude of vibration extending under normal operating conditions to an extreme position on either side of the rest position, and a contact also connected to the secondary winding and located in the path of said spring contact arm at a point closer to the said extreme position than to the said rest position, and a condenser having its terminals connected across said secondary winding and said pendulum contact arm in series, the dimensions of said condenser requiring several impulses for charging it to full voltage.

4. A voltage pulse generator for supplying voltage pulses, comprising a step-up transformer having a primary winding and a secondary winding, a permanently magnetized spring comprising a pendulum contact arm connected in the circuit of said secondary winding, said spring being mounted adjacent the transformer to be electromagnetically operated by means of the magnetic leakage flux of the transformer, said spring contact arm having a rest position and having a free amplitude of vibration extending under normal operating conditions to an extreme position oneither side of the rest position, and a contact also connected to the secondary winding and located in the path of said spring contact arm at a point closer to the said extreme position than to the said rest position, a short circuited winding on said transformer having a reactive value enabling the contact engagement of said pendulum contact arm to take place when the secondary voltage of said transformer reaches its maxima, and a condenser having its terminals connected across said secondary winding and said pendulum contact arm in series, the dimensions of said condenser requiring several impulses for charging it to full voltage.

5. In a voltage pulse generator as claimed in claim 1, and including a spark gap in combination with said condenser for producing pulse voltages.

6. A voltage pulse generator for supplying voltage pulses, comprising a step-up transformer having a primary winding and a secondary winding, a permanently magnetized spring comprising a pendulum contact arm connected in the circuit of said secondary winding, said spring being mounted adjacent the transformer to be electromagnetically operated by means of the magnetic leakage flux of the transformer, said spring contact arm having a rest position and having a, tree amplitude of vibration extending under normal operating conditions to an extreme position on either side of the rest position, and a contact also connected to the secondary winding and located in the path of said spring contact arm at a point closer to the said extreme position than to the said rest position, and voltage doublingmeans connected in said secondary circuit and comprising a condenser chargeable during one half of each cycle and another condenser chargeable during the other half of each cycle, said condensers being connected in series so as to produce across their remote terminals a voltage approximately equal to twice that produced by said transformer.

JOHAN TORSTEN WESTIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,199,494 Pfeifier Sept. 26, 1916 1,259,160 Strong et a1 Mar. 12, 1918 1,682,748 Fayer Sept. 4, 1928 1,768,750 Dicke July 1, 1930 1,920,150 Rockwell July 25, 1933 1,961,841 Bradley June 5, 1934 2,113,762 James Apr. 12, 1938 2,141,869 Konig Dec. 27, 1938 2,146,229 Riepl Feb. 7, 1939 2,184,315 Peters et al. Dec. 26, 1939 2,210,211 Levenberg Aug. 6, 1940 2,315,757 Wenger Apr. 6, 1943 2,316,211 Agnew et al Apr. 13, 1943 2,343,300 Klumb Mar. 7, 1944 2,390,946 Kneisley Dec. 11, 1945 FOREIGNPATENTS Number Country Date 548,243 France Mar. 6, 1922 OTHER REFERENCES Electric Fences, by C. F. Dalziel, A. I. E. E. Tech. Paper -2, 33 West 39th Street, N. Y., N. Y. (esp.pp.5and 16). 

